espsystem: Rearchitecture and fix eh_frame_parser bugs

eh_frame_parser is architecture independent, thus the files have
been rearchitectured. Some bugs have been fixed in the test.
A README file has also been added to eh_frame_parser host test
directory.

eh_frame_parser is now able to detect empty gaps in .eh_frame_hdr
table (missing DWARF information).
Fix a bug occuring when parsing backtraces originated from abort().
Fix build missing dependencies issue.
pull/7307/head
Omar Chebib 2021-02-07 15:03:51 +08:00
rodzic b967dc0dbf
commit 0771bd1711
24 zmienionych plików z 293 dodań i 111 usunięć

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@ -355,3 +355,10 @@ test_log:
- cd ${IDF_PATH}/components/log/host_test/log_test
- idf.py build
- build/test_log_host.elf
test_eh_frame_parser:
extends: .host_test_template
script:
- cd ${IDF_PATH}/components/esp_system/test_eh_frame_parser
- make
- ./eh_frame_test

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@ -15,6 +15,7 @@ unset(link_options)
# Add the following build specifications here, since these seem to be dependent
# on config values on the root Kconfig.
if(NOT BOOTLOADER_BUILD)
if(CONFIG_COMPILER_OPTIMIZATION_SIZE)

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@ -118,6 +118,6 @@ REGION_ALIAS("rtc_data_location", rtc_iram_seg );
#endif
#if CONFIG_ESP_SYSTEM_USE_EH_FRAME
ASSERT ((_eh_frame_end > _eh_frame), "Error: eh_frame size is null!");
ASSERT ((_eh_frame_hdr_end > _eh_frame_hdr), "Error: eh_frame_hdr size is null!");
ASSERT ((__eh_frame_end > __eh_frame), "Error: eh_frame size is null!");
ASSERT ((__eh_frame_hdr_end > __eh_frame_hdr), "Error: eh_frame_hdr size is null!");
#endif

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@ -339,22 +339,28 @@ SECTIONS
*(.srodata.*)
_thread_local_end = ABSOLUTE(.);
_rodata_reserved_end = ABSOLUTE(.);
. = ALIGN(4);
. = ALIGN(ALIGNOF(.eh_frame));
} > default_rodata_seg
.eh_frame :
/* Keep this section shall be at least aligned on 4 */
.eh_frame : ALIGN(8)
{
_eh_frame = ABSOLUTE(.);
__eh_frame = ABSOLUTE(.);
KEEP (*(.eh_frame))
_eh_frame_end = ABSOLUTE(.);
} > drom0_0_seg
__eh_frame_end = ABSOLUTE(.);
/* Guarantee that this section and the next one will be merged by making
* them adjacent. */
. = ALIGN(ALIGNOF(.eh_frame_hdr));
} > default_rodata_seg
.eh_frame_hdr :
/* To avoid any exception in C++ exception frame unwinding code, this section
* shall be aligned on 8. */
.eh_frame_hdr : ALIGN(8)
{
_eh_frame_hdr = ABSOLUTE(.);
__eh_frame_hdr = ABSOLUTE(.);
KEEP (*(.eh_frame_hdr))
_eh_frame_hdr_end = ABSOLUTE(.);
} > drom0_0_seg
__eh_frame_hdr_end = ABSOLUTE(.);
} > default_rodata_seg
.flash.rodata_noload (NOLOAD) :
{

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@ -116,3 +116,8 @@ REGION_ALIAS("rtc_data_location", rtc_iram_seg );
ASSERT(_flash_rodata_dummy_start == ORIGIN(default_rodata_seg),
".flash_rodata_dummy section must be placed at the beginning of the rodata segment.")
#endif
#if CONFIG_ESP_SYSTEM_USE_EH_FRAME
ASSERT ((__eh_frame_end > __eh_frame), "Error: eh_frame size is null!");
ASSERT ((__eh_frame_hdr_end > __eh_frame_hdr), "Error: eh_frame_hdr size is null!");
#endif

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@ -289,9 +289,6 @@ SECTIONS
*(.gcc_except_table .gcc_except_table.*)
*(.gnu.linkonce.e.*)
*(.gnu.version_r)
. = (. + 3) & ~ 3;
__eh_frame = ABSOLUTE(.);
KEEP(*(.eh_frame))
. = (. + 7) & ~ 3;
/*
* C++ constructor and destructor tables
@ -342,7 +339,27 @@ SECTIONS
*(.srodata.*)
_thread_local_end = ABSOLUTE(.);
_rodata_reserved_end = ABSOLUTE(.);
. = ALIGN(4);
. = ALIGN(ALIGNOF(.eh_frame));
} > default_rodata_seg
/* Keep this section shall be at least aligned on 4 */
.eh_frame : ALIGN(4)
{
__eh_frame = ABSOLUTE(.);
KEEP (*(.eh_frame))
__eh_frame_end = ABSOLUTE(.);
/* Guarantee that this section and the next one will be merged by making
* them adjacent. */
. = ALIGN(ALIGNOF(.eh_frame_hdr));
} > default_rodata_seg
/* To avoid any exception in C++ exception frame unwinding code, this section
* shall be aligned on 8. */
.eh_frame_hdr : ALIGN(8)
{
__eh_frame_hdr = ABSOLUTE(.);
KEEP (*(.eh_frame_hdr))
__eh_frame_hdr_end = ABSOLUTE(.);
} > default_rodata_seg
/* Marks the end of IRAM code segment */

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@ -1,5 +1,6 @@
idf_build_get_property(target IDF_TARGET)
set(priv_requires efuse)
set(requires soc)
if(${target} STREQUAL "esp32")
list(APPEND requires efuse)
@ -17,7 +18,10 @@ if(NOT BOOTLOADER_BUILD)
"mac_addr.c"
"sleep_modes.c"
"regi2c_ctrl.c")
list(APPEND priv_requires esp_ipc)
list(APPEND priv_requires esp_ipc)
else()
# Requires "_esp_error_check_failed()" function
list(APPEND priv_requires "esp_system")
endif()
idf_component_register(SRCS ${srcs}

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@ -1,14 +1,15 @@
idf_build_get_property(target IDF_TARGET)
set(srcs)
set(srcs "esp_err.c")
if(CONFIG_IDF_ENV_FPGA)
list(APPEND srcs "fpga_overrides.c")
endif()
if(BOOTLOADER_BUILD)
# Bootloader relies on some Kconfig options defined in esp_system.
idf_component_register(SRCS "${srcs}")
# "_esp_error_check_failed()" requires spi_flash module
# Bootloader relies on some Kconfig options defined in esp_system.
idf_component_register(SRCS "${srcs}" REQUIRES spi_flash)
else()
list(APPEND srcs "crosscore_int.c"
"esp_err.c"
@ -26,6 +27,10 @@ else()
list(APPEND srcs "dbg_stubs.c")
endif()
if(CONFIG_ESP_SYSTEM_USE_EH_FRAME)
list(APPEND srcs "eh_frame_parser.c")
endif()
idf_component_register(SRCS "${srcs}"
INCLUDE_DIRS include
PRIV_REQUIRES spi_flash

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@ -98,10 +98,12 @@ menu "ESP System Settings"
default n
depends on IDF_TARGET_ARCH_RISCV
help
Generate DWARF information in the resulting binary to perform backtracing when panics occur. Activating
this option will activate asynchronous frame unwinding and generation of both .eh_frame and .eh_frame_hdr
sections, resulting in a bigger binary size (20% to 100% larger). This option shall be not be used for
production.
Generate DWARF information for each function of the project. These information will parsed and used to
perform backtracing when panics occur. Activating this option will activate asynchronous frame unwinding
and generation of both .eh_frame and .eh_frame_hdr sections, resulting in a bigger binary size (20% to
100% larger). The main purpose of this option is to be able to have a backtrace parsed and printed by
the program itself, regardless of the serial monitor used.
This option shall NOT be used for production.
menu "Memory protection"

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@ -25,13 +25,14 @@
* http://dwarfstd.org/Download.php
*/
#include "port/eh_frame_parser.h"
#include "port/eh_frame_parser_impl.h"
#include "eh_frame_parser.h"
#include "esp_private/panic_internal.h"
#include <string.h>
#if CONFIG_ESP_SYSTEM_USE_EH_FRAME
#include "eh_frame_parser_impl.h"
/**
* @brief Dimension of an array (number of elements)
*/
@ -90,8 +91,8 @@
/**
* @brief Pointers to both .eh_frame_hdr and .eh_frame sections.
*/
#define EH_FRAME_HDR_ADDR (&_eh_frame_hdr)
#define EH_FRAME_ADDR (&_eh_frame)
#define EH_FRAME_HDR_ADDR (&__eh_frame_hdr)
#define EH_FRAME_ADDR (&__eh_frame)
/**
* @brief Structure of .eh_frame_hdr section header.
@ -259,8 +260,8 @@ typedef struct {
* @brief Symbols defined by the linker.
* Retrieve the addresses of both .eh_frame_hdr and .eh_frame sections.
*/
extern char _eh_frame_hdr;
extern char _eh_frame;
extern char __eh_frame_hdr;
extern char __eh_frame;
/**
* @brief Decode multiple bytes encoded in LEB128.
@ -439,22 +440,22 @@ static const table_entry* esp_eh_frame_find_entry(const table_entry* sorted_tabl
/* Signed comparisons. */
const int32_t sfun_addr = (int32_t) fun_addr;
const int32_t snxt_addr = (int32_t) nxt_addr;
if (sfun_addr <= ra && snxt_addr > ra)
found = true;
else if (snxt_addr <= ra)
begin = middle + 1;
else
end = middle;
if (sfun_addr <= ra && snxt_addr > ra)
found = true;
else if (snxt_addr <= ra)
begin = middle + 1;
else
end = middle;
} else {
/* Unsigned comparisons. */
const uint32_t ura = (uint32_t) ra;
if (fun_addr <= ura && nxt_addr > ura)
found = true;
else if (nxt_addr <= ura)
begin = middle + 1;
else
end = middle;
if (fun_addr <= ura && nxt_addr > ura)
found = true;
else if (nxt_addr <= ura)
begin = middle + 1;
else
end = middle;
}
middle = (end + begin) / 2;
@ -799,10 +800,45 @@ static uint32_t esp_eh_frame_restore_caller_state(const uint32_t* fde,
EXECUTION_FRAME_SP(*frame) = cfa_addr;
/* If the frame was not available, it would be possible to retrieve the return address
* register thanks to CIE structure. */
return EXECUTION_FRAME_REG(frame, ra_reg);
* register thanks to CIE structure.
* The return address points to the address the PC needs to jump to. It
* does NOT point to the instruction where the routine call occured.
* This can cause problems with functions without epilogue (i.e. function
* which last instruction is a function call). This happens when compiler
* optimization are ON or when a function is marked as "noreturn".
*
* Thus, in order to point to the call/jal instruction, we need to
* subtract at least 1 byte but not more than an instruction size.
*/
return EXECUTION_FRAME_REG(frame, ra_reg) - 2;
}
/**
* @brief Test whether the DWARF information for the given PC are missing or not.
*
* @param fde FDE associated to this PC. This FDE is the one found thanks to
* `esp_eh_frame_find_entry()`.
* @param pc PC to get information from.
*
* @return true is DWARF information are missing, false else.
*/
static bool esp_eh_frame_missing_info(const uint32_t* fde, uint32_t pc) {
if (fde == NULL) {
return true;
}
/* Get the range of this FDE entry. It is possible that there are some
* gaps between DWARF entries, in that case, the FDE entry found has
* indeed an initial_location very close to PC but doesn't reach it.
* For example, if FDE initial_location is 0x40300000 and its length is
* 0x100, but PC value is 0x40300200, then some DWARF information
* are missing as there is a gap.
* End the backtrace. */
const uint32_t initial_location = ((uint32_t) &fde[ESP_FDE_INITLOC_IDX] + fde[ESP_FDE_INITLOC_IDX]);
const uint32_t range_length = fde[ESP_FDE_RANGELEN_IDX];
return (initial_location + range_length) <= pc;
}
/**
* @brief When one step of the backtrace is generated, output it to the serial.
@ -824,10 +860,12 @@ void __attribute__((weak)) esp_eh_frame_generated_step(uint32_t pc, uint32_t sp)
*
* @param frame_or Snapshot of the CPU registers when the CPU stopped its normal execution.
*/
void esp_eh_frame_print_backtrace(const ExecutionFrame *frame_or)
void esp_eh_frame_print_backtrace(const void *frame_or)
{
assert(frame_or != NULL);
static dwarf_regs state = { 0 };
ExecutionFrame frame = *frame_or;
ExecutionFrame frame = *((ExecutionFrame*) frame_or);
uint32_t size = 0;
uint8_t* enc_values = NULL;
bool end_of_backtrace = false;
@ -865,16 +903,23 @@ void esp_eh_frame_print_backtrace(const ExecutionFrame *frame_or)
const table_entry* from_fun = esp_eh_frame_find_entry(sorted_table, fde_count,
table_enc, EXECUTION_FRAME_PC(frame));
if (from_fun == 0) {
/* Get absolute address of FDE entry describing the function where PC left of. */
uint32_t* fde = NULL;
if (from_fun != NULL) {
fde = esp_eh_frame_decode_address(&from_fun->fde_addr, table_enc);
}
if (esp_eh_frame_missing_info(fde, EXECUTION_FRAME_PC(frame))) {
/* Address was not found in the list. */
panic_print_str("\r\nBacktrace ended abruptly: cannot find DWARF information for"
" instruction at address 0x");
panic_print_hex(EXECUTION_FRAME_PC(frame));
panic_print_str("\r\n");
break;
}
/* Get absolute address of FDE entry describing the function where PC left of. */
const uint32_t* fde = esp_eh_frame_decode_address(&from_fun->fde_addr, table_enc);
/* Clean and set the DWARF register structure.
* TODO: Initialization should be done by the instruction contained by the CIE associated to the FDE. */
/* Clean and set the DWARF register structure. */
memset(&state, 0, sizeof(dwarf_regs));
const uint32_t prev_sp = EXECUTION_FRAME_SP(frame);

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@ -15,13 +15,21 @@
#ifndef EH_FRAME_PARSER_H
#define EH_FRAME_PARSER_H
#include "eh_frame_parser_impl.h"
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief Print backtrace for the given execution frame.
*
* @param frame_or Snapshot of the CPU registers when the CPU stopped its normal execution.
* @param frame_or Snapshot of the CPU registers when the program stopped its
* normal execution. This frame is usually generated on the
* stack when an exception or an interrupt occurs.
*/
void esp_eh_frame_print_backtrace(const ExecutionFrame *frame_or);
void esp_eh_frame_print_backtrace(const void *frame_or);
#ifdef __cplusplus
}
#endif
#endif

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@ -1,4 +1,10 @@
target_include_directories(${COMPONENT_LIB} PRIVATE . include PUBLIC soc)
set(INCLUDE_FILES "include" . include PUBLIC soc)
if(CONFIG_IDF_TARGET_ARCH_RISCV)
list(APPEND INCLUDE_FILES "include/riscv")
endif()
target_include_directories(${COMPONENT_LIB} PRIVATE ${INCLUDE_FILES})
target_include_directories(${COMPONENT_LIB} PUBLIC public_compat)
set(srcs "cpu_start.c" "panic_handler.c" "brownout.c")

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@ -14,6 +14,8 @@
// limitations under the License.
#include <stdio.h>
#include "esp_spi_flash.h"
#include "soc/extmem_reg.h"
#include "esp_private/panic_internal.h"
#include "esp_private/panic_reason.h"
@ -29,7 +31,7 @@
#endif
#if CONFIG_ESP_SYSTEM_USE_EH_FRAME
#include "port/eh_frame_parser.h"
#include "eh_frame_parser.h"
#endif
@ -324,11 +326,7 @@ void panic_arch_fill_info(void *frame, panic_info_t *info)
info->frame = &regs;
}
void panic_print_backtrace(const void *frame, int core)
{
#if CONFIG_ESP_SYSTEM_USE_EH_FRAME
esp_eh_frame_print_backtrace(frame);
#else
static void panic_print_basic_backtrace(const void *frame, int core) {
// Basic backtrace
panic_print_str("\r\nStack memory:\r\n");
uint32_t sp = (uint32_t)((RvExcFrame *)frame)->sp;
@ -343,6 +341,20 @@ void panic_print_backtrace(const void *frame, int core)
panic_print_str(y == per_line - 1 ? "\r\n" : " ");
}
}
}
void panic_print_backtrace(const void *frame, int core)
{
#if CONFIG_ESP_SYSTEM_USE_EH_FRAME
if (!spi_flash_cache_enabled()) {
panic_print_str("\r\nWarning: SPI Flash cache is disabled, cannot process eh_frame parsing. "
"Falling back to basic backtrace.\r\n");
panic_print_basic_backtrace(frame, core);
} else {
esp_eh_frame_print_backtrace(frame);
}
#else
panic_print_basic_backtrace(frame, core);
#endif
}

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@ -1,27 +0,0 @@
// Copyright 2020 Espressif Systems (Shanghai) PTE LTD
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef EH_FRAME_PARSER_H
#define EH_FRAME_PARSER_H
#include "eh_frame_parser_impl.h"
/**
* @brief Print backtrace for the given execution frame.
*
* @param frame_or Snapshot of the CPU registers when the CPU stopped its normal execution.
*/
void esp_eh_frame_print_backtrace(const ExecutionFrame *frame_or);
#endif

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@ -7,7 +7,6 @@ set(srcs "clk.c"
"../../arch/riscv/expression_with_stack_asm.S"
"../../arch/riscv/panic_arch.c")
set(srcs ${srcs} "../../arch/riscv/eh_frame_parser.c")
add_prefix(srcs "${CMAKE_CURRENT_LIST_DIR}/" ${srcs})
target_sources(${COMPONENT_LIB} PRIVATE ${srcs})

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@ -14,7 +14,7 @@
# limitations under the License.
CC=gcc
CFLAGS=-W -fasynchronous-unwind-tables -I. -std=c99 -g -DCONFIG_ESP_SYSTEM_USE_EH_FRAME -m32
CFLAGS=-W -fasynchronous-unwind-tables -I. -I../include/ -std=c99 -g -DCONFIG_ESP_SYSTEM_USE_EH_FRAME -m32
LDFLAGS=-Wl,--eh-frame-hdr -m32 -g -Tlinker.ld -no-pie
OBJECTS=objs/eh_frame_parser.o objs/main.o
HEADERS=eh_frame_parser_impl.h

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@ -0,0 +1,42 @@
# Host test for EH_FRAME_PARSER
This test is meant to be run on a Linux x86(_64) host. The main purpose is to
trigger a SIGSEV (NULL pointer) exception at runtime in order to generate the
backtrace. It is then checked that the functions in the call stack are indeed
correctly determined in the right order.
## Requirements
A Linux host, x86 or x86_64. In any case, the example will be compiled with
the option `-m32`, it is then required to have gcc multilibs.
## Compile the example
To compile the example, simply type:
```
make
```
## Run the code
Execute the binary generated:
```
./eh_frame_test
```
If everything goes well, the output should be as is:
```
All tests passed
```
## Known issue
DWARF instructions in `x86` binaries include the instruction `DW_CFA_expression`.
However, this instruction is not supported by the parser, this is why the test
may print the following message:
```
Unsupported DWARF opcode 0: 0x10
```
This is not a big problem as the functions implemented for testing the backtrace
will not generate unimplemented DWARF instructions.

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@ -18,12 +18,12 @@ SECTIONS
{
.eh_frame_hdr :
{
_eh_frame_hdr = ABSOLUTE(.);
*(.eh_frame_hdr) *(.eh_frame_entry .eh_frame_entry.*)
__eh_frame_hdr = ABSOLUTE(.);
*(.eh_frame_hdr) *(.eh_frame_entry .eh_frame_entry.*)
}
.eh_frame : ONLY_IF_RO
{
_eh_frame = ABSOLUTE(.);
__eh_frame = ABSOLUTE(.);
KEEP (*(.eh_frame)) *(.eh_frame.*)
}
}

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@ -20,7 +20,8 @@
* parsing `eh_frame` and `eh_frame_hdr`.
*/
#define _POSIX_C_SOURCE 199309L
#define _POSIX_C_SOURCE 200809L
#define _DEFAULT_SOURCE
#include <stdio.h>
#include <signal.h>
#include <string.h>
@ -29,7 +30,8 @@
#include <stdbool.h>
#include <assert.h>
#include <ucontext.h>
#include "port/eh_frame_parser.h"
#include "../include/eh_frame_parser.h"
#include "eh_frame_parser_impl.h"
/**
* @brief Index of x86 registers in `greg_t` structure.
@ -53,7 +55,12 @@
* @brief Number which will determine the depth of the call stack.
* Check `main()` for more information.
*/
#define NUMBER_TO_TEST (4)
#define NUMBER_TO_TEST (4)
/**
* @brief Number of iteration for function `esp_eh_frame_generated_step`.
*/
#define NUMBER_OF_ITERATION (2 * NUMBER_TO_TEST + 2 + 1)
/**
* @brief Define a simple linked list type and initialize one.
@ -106,7 +113,7 @@ struct functions_info funs[] = {
/**
* @brief Test whether the address passed as PC is part of the function which
* name is `funciton_name`. The global array `funs` is used.
* name is `function_name`. The global array `funs` is used.
*
* @param pc Program counter to test. (address in the program)
* @param function_name Function name to check the address of.
@ -126,19 +133,20 @@ bool is_pc_in_function(const uint32_t pc, const char* function_name)
return false;
}
/**
* @brief Number of times `esp_eh_frame_generated_step` is called.
*/
static uint32_t iteration = 1;
/**
* @brief Override the default function called when a backtrace step is
* generated.
*/
void esp_eh_frame_generated_step(uint32_t pc, uint32_t sp) {
/* Number of times this function has been entered. */
static uint32_t iteration = 1;
/* The first PC in the backtrace are calls to `browse_list()`.
* +2 is due to the fact that the list contains all the numbers
/* The first PCs in the backtrace are calls to `browse_list()` + 2.
* This is due to the fact that the list contains all the numbers
* between NUMBER_TO_TEST to 0 included. Moreover, another call
* is made when we meet the NULL pointer.
*/
* is made when we meet the NULL pointer. */
if (iteration > 0 && iteration <= (NUMBER_TO_TEST + 2)) {
assert(is_pc_in_function(pc, "browse_list"));
} else {
@ -151,13 +159,15 @@ void esp_eh_frame_generated_step(uint32_t pc, uint32_t sp) {
* browse_list (NUMBER_TO_TEST + 2 iterations), is_even
* (NUMBER_TO_TEST/2 calls) and is_odd (NUMBER_TO_TEST/2 calls) calls.
*/
if (iteration > (2 * NUMBER_TO_TEST + 2))
if (iteration >= NUMBER_OF_ITERATION)
return;
else if (iteration % 2 == 0)
assert(is_pc_in_function(pc, "is_odd"));
else
assert(is_pc_in_function(pc, "is_even"));
}
/* Number of times this function has been entered. */
iteration++;
}
@ -175,7 +185,7 @@ void signal_handler(int signal, siginfo_t *info, void *ucontext) {
* Indeed, the registers index defined in ucontext.h are NOT the same
* the registers index DWARF is expecting. */
ucontext_t* context = (ucontext_t*) ucontext;
greg_t *gregset = context->uc_mcontext.__gregs;
greg_t *gregset = context->uc_mcontext.gregs;
x86ExcFrame frame = {
.eax = gregset[REG_EAX],
.ecx = gregset[REG_ECX],
@ -195,8 +205,15 @@ void signal_handler(int signal, siginfo_t *info, void *ucontext) {
*/
esp_eh_frame_print_backtrace(&frame);
/* No assert has been triggered, the backtrace succeeded. */
printf("\e[32m\e[1mAll tests passed \e[0m\r\n");
/* No assert has been triggered, the backtrace succeeded if the number of
* iterations of function `esp_eh_frame_generated_step` is correct. */
if (iteration == NUMBER_OF_ITERATION) {
printf("\e[32m\e[1mAll tests passed \e[0m\r\n");
} else {
printf("\e[31m\e[1mWrong length of backtrace (%d iteration, expected %d) \e[0m\r\n",
iteration, NUMBER_OF_ITERATION);
exit(1);
}
/* Everything went fine, exit normally. */
exit(0);
@ -298,6 +315,7 @@ int main (int argc, char** argv)
int res = sigaction(SIGSEGV, &sig, NULL);
if (res) {
perror("Could not override SIGSEV signal");
return 1;
}
/* Trigger the segmentation fault with a complex backtrace. */

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@ -1,12 +1,13 @@
idf_build_get_property(target IDF_TARGET)
set(srcs "wdt_hal_iram.c"
"mpu_hal.c")
"mpu_hal.c"
"cpu_hal.c")
set(includes "${target}/include" "include" "platform_port/include")
if(NOT BOOTLOADER_BUILD)
list(APPEND srcs
"cpu_hal.c"
"rmt_hal.c"
"rtc_io_hal.c"
"spi_hal.c"

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@ -207,6 +207,37 @@ If :doc:`IDF Monitor <tools/idf-monitor>` is used, Program Counter values will b
MSTATUS : 0x00001881 MTVEC : 0x40380001 MCAUSE : 0x00000007 MTVAL : 0x00000000
MHARTID : 0x00000000
Moreover, it is also capable of generating and printing a backtrace thanks to the stack dump provided by the board in the panic handler.
The output looks like this:
::
Backtrace:
0x42006686 in bar (ptr=ptr@entry=0x0) at ../main/hello_world_main.c:18
18 *ptr = 0x42424242;
#0 0x42006686 in bar (ptr=ptr@entry=0x0) at ../main/hello_world_main.c:18
#1 0x42006692 in foo () at ../main/hello_world_main.c:22
#2 0x420066ac in app_main () at ../main/hello_world_main.c:28
#3 0x42015ece in main_task (args=<optimized out>) at /Users/user/esp/components/freertos/port/port_common.c:142
#4 0x403859b8 in vPortEnterCritical () at /Users/user/esp/components/freertos/port/riscv/port.c:130
#5 0x00000000 in ?? ()
Backtrace stopped: frame did not save the PC
While this is very handy efficient, it requires the user to use :doc:`IDF Monitor <tools/idf-monitor>`. Thus, in order to generate and print a backtrace while using another monitor program, it is possible to activate :ref:`CONFIG_ESP_SYSTEM_USE_EH_FRAME` option from the menuconfig.
This option will let the compiler generate DWARF information for each function of the project. Then, when a CPU exception occurs, the panic handler will parse these data and determine the backtrace of the task that failed. The output looks like this:
::
Backtrace: 0x42009e9a:0x3fc92120 0x42009ea6:0x3fc92120 0x42009ec2:0x3fc92130 0x42024620:0x3fc92150 0x40387d7c:0x3fc92160 0xfffffffe:0x3fc92170
These PC:SP pairs represent PC, the Program Counter and SP, the Stack Pointer for each stack frame of the current task.
The main benefit of this option is that this trace is generate by the board itself. Its drawback is that it results in a larger compiled binary, with an increase that can go from 20% to 100%. Finally, it is highly advised to not use this option for production as it results in the presence of debug information within the final binary.
To find the location where a fatal error has happened, look at the lines which follow the "Backtrace" line. Fatal error location is the top line, and subsequent lines show the call stack.
.. _GDB-Stub:
@ -489,4 +520,4 @@ The types of errors reported by UBSAN can be as follows:
* - ``builtin_unreachable``
- ``__builtin_unreachable`` function called.
* - ``pointer_overflow``
- Overflow in pointer arithmetic.
- Overflow in pointer arithmetic.